The present invention relates to the technical field of seat belt retractors and seat belt apparatuses provided with such seat belt retractors, which perform at least one of taking up and delivering of a seat belt by causing an electric motor to rotate a spool and, more particularly, to the technical field of a seat belt retractor and a seat belt apparatus that employs such a seat belt retractor in which the electric motor is controlled by an electronic control unit (ECU). References to right and left hand sides in the description correspond to those in the attached figures.
Seat belt apparatuses that have been provided in vehicles such as automobiles for years prevent an occupant from being ejected from a seat by restraining the occupant using a seat belt in the event of an emergency such as a vehicle collision. Such seat belt apparatuses are provided with a seat belt retractor for taking up the seat belt. In such a seat belt retractor, the seat belt is wound around a spool when not being worn by the occupant, and is delivered and worn by the occupant when an attempt to wear the seat belt is made by the occupant. In the event of an emergency, the locking mechanism of the seat belt retractor is activated to prevent the spool from rotating in the direction in which the seat belt is delivered, thereby preventing the seat belt from being delivered. This allows the seat belt to restrain the occupant in the event of an emergency.
As a conventional seat belt apparatus, a seat belt apparatus provided with a seat belt retractor that performs taking up of a seat belt by rotating and controlling a spool with an electric motor has been publicly made known in Japanese Unexamined Patent Application Publication No. 2001-130377.
FIG. 3 is a diagram exemplifying a conventional seat belt apparatus described in Japanese Unexamined Patent Application Publication No. 2001-130377. FIG. 4 is a diagram exemplifying a seat belt retractor used in such a seat belt apparatus.
As shown in FIGS. 3 and 4, the seat belt apparatus 1, as is the case with a conventional known three-point seat belt, includes a seat belt 3 that is connected at an end thereof, namely, a belt anchor 3a thereof to a body floor or a vehicle seat, a seat belt retractor 6 secured to the vehicle body for performing taking up of the seat belt 3 by causing an electric motor 4 to rotate a spool 5, a guide anchor 7 for guiding the seat belt 3 drawn out of the seat belt retractor 6 to an occupant's shoulder, a tongue 8 slidably supported by the seat belt 3 guided through the guide anchor 7, and a buckle 9, secured to the vehicle floor or the vehicle seat 2, which the tongue 8 is detachably inserted into and engaged with.
As is the case with a conventional known seat belt retractor, the seat belt retractor 6 according to an embodiment includes an inverted C shaped frame 10 having a back plate 10a and right and left side walls 10b, 10c projecting from both ends of the back plate 10a, respectively, the seat belt 3, the spool 5 rotatably supported by the frame 10 for taking up the seat belt 3, a spring device 11 supported by the frame 10 for normally urging the spool 5 in the direction in which the seat belt is taken up, a motor 4, as driving means, supported by the frame 10 for rotating the spool 5, a power transmission mechanism 12 supported by the frame 10 for changing the speed of the motor 4 and transmitting it to the spool 5, and a circuit board 14 supported by a cover 13 provided on the left side wall 10b of the frame 10 and having a printed circuit 14a for driving and controlling the motor 4. Accordingly, taking up of the seat belt 3 is performed by an urging force only of the spring device 11 or the urging force of the spring device 11 and the driving force of the motor 4.
Although not illustrated in FIG. 4, the frame is provided at the right side wall 10c thereof with a vehicle sensor (deceleration sensing mechanism) that is activated when a vehicle is subjected to a deceleration greater than a predetermined level in the event of a vehicle collision or the like, a conventional known webbing sensor that is activated when the seat belt 3 is delivered more quickly and rapidly than normal seat belt delivery (more natural delivery of a seat belt when an occupant is normally wearing the seat belt), and a conventional known locking mechanism that is activated in conjunction with activation of the vehicle sensor and the webbing sensor for locking the rotation of the spool 5 in the direction in which the seat belt is delivered.
Although the circuit board 14 is not directly disclosed in Japanese Unexamined Patent Application Publication No. 2001-130377, a vehicle side connector that is connected to a power supply is provided at a predetermined position on the vehicle body. The circuit board 14 is electrically connected to such a vehicle side connector, and an intermediate harness is typically used for that connection. The use of the intermediate harness has caused the layout of the circuit board 14 to be determined for years, irrespective of the location of the vehicle side connector.
However, the conventional seat belt retractor requires the intermediate harness to electrically connect the circuit board 14 to the vehicle side connector, resulting in an increased number of components and resultant increased costs, which makes more troublesome assembling of the seat belt retractor 6 provided integrally with the circuit board 14.